Apparatus for the fabrication of pre-stressed concrete construction elements



Jan. 13, 1970 A. GARABOUX 3,488,816

APPARATUS FQR THE FABRICATION OF PRE-STRESSED CONCRETE CONSTRUCTION ELEMENTS 1964 8 Sheets-Sheet 1 Original Filed Nov. 4,

A. GARABOUX 3,488,816 APPARATUS FOR THE FABRICATION OF PRE-STRESSED Jan. 13, 1970 CONCRETE CONSTRUCTION ELEMENTS 8 Sheets-Sheet 2 Original Filed Nov. 4, 1964 l I I l t I I I 1 l l I l l l IL Jan. 13, 1970 A. GARABOUX ,488,816

APPARATUS FOR THE FABRICATION OF FEE-STRESSED CONCRETE CONSTRUCTION ELEMENTS Original Filed Nov i, 1964 v 8 Sheets-Sheet 3 Jan, 13, 1970 A. GARABOUX 3,488,816

APPARATUS FOR THE FABRICATION OF FEE-STRESSED CONCRETE CONSTRUCTION ELEMENTS Original Filed Nov. 4, 1964 8 Sheets-Sheet 4 A. GARABOUX 3,488,816 APPARATUS FOR THE FABRICATION OF FEE-STRESSED Jan. 13, 1970 CONCRETE CONSTRUCTION ELEMENTS Original Filed Nov. 4, 1964 8 Sheets-Sheet mm wmwwwmw mhw 8m. wow RM 8% aw? EN 8 0 5,, 9% 8m HXAQN am EN Rw a A2 on Q3 QQ @mw www Jan. 13, 1970 A. GARABOUX 3,488,816

APPARATUS FOR THE FABRICATION OF PRE-STRESSED CONCRETBCONSTRUCTION ELEMENTS Original Filed Nov. 1964 8 Sheets-Sheet 7 Jan. 13, 1970 A. GARABOUX APPARATUS FOR THE FABRICATION OF FEE-STRESSED CONCRETE CONSTRUCTION ELEMENTS Original Filed Nov. 4, 1964 8 Sheets-Sheet 8 mww QQN Wnw www United States Patent Int. Cl. nzsb 7/00 U.S. Cl. 25-41 16 Claims ABSTRACT OF THE DISCLOSURE An apparatus for semi-automatically fabricating concrete bars having a resilient reinforcing rod. A pouring mold is provided having a plurality of longitudinally aligned end abutting channel iron pairs with their webs vertically oriented and facing one another and having means to rigidly connect each of the irons to the irons abutting it. Adjustment means are further provided to vary the distance between the webs and means are provided for the passage of a reinforcing rod which is adapted to be placed under tension and vibratory means are associated with the mold for inducing vibrations in the concrete while the same is being poured.

This is a division of application Ser. No. 408,987, filed Nov. 4, 1964, now abandoned.

The present invention relates to an apparatus for the construction of pre-stressed concrete construction elements having a prismatic form and known as bars or triangles.

The various methods of construction of concrete flooring utilizing spaced bars is well known. According to these methods the concrete is poured either in permanently placed forms supported by the bars or in recoverable forms.

The present invention concerns apparatus for the fabrication of bars of the general type, just defined; it permits a great improvement in the conditions of fabrication of these bars and, particularly, in their price.

According to the process for fabricating such an element from pre-stressed concrete, a metallic support reinforcement rod is disposed along the axis of symmetry of the fabrication mold in such a way that the ends of this reinforcement extend beyond the extremities of the mold; the rod is placed under tension; the concrete is poured into the mold while a secondary seam reinforcement is disposed along the upper portion part of the mold and the tension on the central reinforcement is released when the concrete has become sufficiently hardened to support the compression stress exerted by the released reinforcement. This process is characterized in that the cen ral reinforcement is subjected to a tension which is just slightly less than its rupture point and which is constantly maintained at this value, and the concrete is poured into the mold while subjecting it to a continuous vibration.

It should be noted in accordance with the preceding discussion, that the process of the present invention consists in obtaining, by cold-drawing for example, an increase of the elastic limit of the armature, so as to place it in the neighborhood of its rupture point. It thus becomes possible, for this type of fabrication, to utilize steel whose resistance to rupture is as low as 75 kg./cm.

According to another feature of the process of this invention, the reinforcement is subjected to a tension which reaches 90 to 95% of its rupture limit.

According to another feature of this process, the vibration of the concrete is produced by applying a vibration to the tensed central reinforcement, which induces a vibration in the concrete.

According to still another feature of this process, the tensed reinforcement is excited in such a way that it vibrates at a harmonic frequency which is substantially higher than the frequency of the vibration generating force.

The present invention resides in means for carrying out the process, these means comprising various forms of pouring molds, means for placing the central reinforcement under tension, and means for inducing vibrations in the concrete.

The present invention also includes the construction.

of such apparatus so as to render at least some of its operations automatic or at least semi-automatic; for example, the placing of the central reinforcement, the pouring of the concrete, and the vibration of the reinforcement and the concrete.

According to another feature of this invention, the pouring mold is constituted by two channel irons having their webs vertical and facing one another, these irons being joined by sheet metal elements, welded to respective irons and rigidly connected together by cross-pieces which permit the distance between the webs to be varied, the length of one mold being equal to the length of several of the concrete bars to be molded, and these latter lengths being defined, in a mold, by end pieces traversed by the central reinforcement and attached thereto after said reinforcement has been placed under tension, the two adjacent end pieces for two successive concrete moldings being spaced apart by an amount equal to twice the distance by which it is desired to have a reinforcement extend beyond the end of its concrete bar.

According to another feature of this invention, each adjacent pair of end pieces is constituted by an assembly to two similar parts each carrying, on the one hand, a framing plate comprising a slit for the placement of the end piece on the reinforcement and the centering of the latter at the bottom of the slit and, on the other hand, an arm rigidly connected to the plate, and perpendicular thereto, the two resulting arms each being parallel to, and on a respective side of, said reinforcement and rigidly attached, at the time when the end pieces are positioned by means of an assembly element which pinches these arms against the tensed reinforcement.

According to another feature of this invention, the means for placing the reinforcements under tension comprise, in combination: a fixed anchoring carriage for one end of each of the reinforcement rods of several, simultaneously used molds comprising clamping means for these rods; a fixed traction carriage for tensing the rods and a fixed carriage for restraining the rods; a traction apparatus supported by the traction carriage and comprising a jack acting on the rods to be tensed and an apparatus for continuously monitoring the tension on the rod.

According to another feature of the invention, the traction apparatus comprises a screw jack operated by an electric motor operating through a speed reducer, said jack also having a hollow screw traversed by the reinforcement, a retaining jaw, gripping the reinforcement being supported by the end of the screw.

According to another feature, the apparatus for continuously monitoring the tension on the central reinforcement is a hydraulic dynamometer, having two barrels coaxially mounted to slide with respect to one another and axially traversed by the reinforcement, the outer barrel carrying a manometer for measuring the pressure of a fluid interposed between the two barrels, one of the barrels being supported by a traction bar and the other barrel serving as a support for a tube surrounding the jack screw and transmitting thereto, in the form of a cornpression, the tensile force applied to the reinforcement by the jack.

According to another characteristic, the means for inducing vibrations in the concrete are constituted by 21 vibrating unit, such as a small pneumatic or electric hammer, acting directly on the tensed reinforcement during the pouring of the concrete and provoking vibrations at harmonic frequencies.

According to another feature, the traction apparatus comprises, in combination: a stand furnished at one end with a pressure tube terminated by a dynamometric chamber; a hollow piston traversed by a reinforcement to be tensed, mounted to slide in an impermeable manner in the dynamometric chamber, and supported by the fixed traction carriage; a manometer for measuring the pressure in the dynamometric chamber; a female screw traversed by the reinforcement to be tensed and slidably mounted in the stand and the pressure tube, this screw carrying, at its end away from the dynamometric chamber, a set of stop jaws for automatically gripping the reinforcement; a toothed wheel coaxial with the female screw and rigidly connected to a nut driving this screw in translation; a reduction motor for driving the toothed wheel; a contactor for the end of the traction travel and a contactor for the end of the return travel of the hollow screw for controlling the driving motor; and a switch responsive to the pressure in the dynamometric chamber for interrupting the power supply to the motor at a predetermined pressure.

The apparatus for rendering certain operations automatic, or at least semi-automatic, comprises, in accordance with the invention, a table, called a traverse table, straddling the entire width of the work area and movable along the longitudinal axis of the construction elements between the ends of this area, these ends being delimited, on the one hand, by the anchoring carriage and, on the other hand, by the restraining and traction carriages; at least one chassis, called a support chassis, disposed on the traverse table and displaceable thereon in a direction perpendicular to the direction of table displacement; means for fixing metallic reinforcement rods to the table; a concrete ladle having a hopper in its lower end and mounted on the chassis; a vibrator for inducing vibrations in the ladle wall portions situated near the pouring opening of the hopper; at least two retractable vibrators mounted in a pivotable manner on the support chassis, to either side of the ladle and along the axis of the tensed reinforcement rods, these vibrators being intended to induce vibrations in said rod; vibrator control means; means for regulating the hopper opening; and means for driving the traverse table.

According to another feature of the invention, the means for fixing the reinforcernent rods on the traverse table are constituted: by a series of pairs of articulated arms, the upper arm of each pair being firmly mounted on the front edge of the table; by a cross-bar connecting together the lower arms of the series of pairs and rigidly connected to the lower end of the front side of these arms; and by a fiat bar capable of being held against the horizontal face of the cross-bar by means of a series of juxtaposed, threaded bolts passing through the fiat bar and anchored in said cross-bar, the arms of each pair of arms joined by means of a knuckle-joint arranged so that the joined lower arms can be either fixed in a vertical position, in which position the upper ends of the lower bars abut against the lower ends of the upper bars, or are moved towards the rear of the table into a raised position, in which position the cross-piece is removed from the plane of the work area.

According to another feature, the traverse table comprises: a rectangular frame, made of channel irons, the longitudinal sides of which are perpendicular to the direction of movement of this table and parallel to the carriages; a series of channel-bars fixed at predetermined distances on the exterior edges of the longit dinal sides,

and perpendicular thereto; covering boards or sheets placed on the bars in such a way as to form a circulation path; cross-pieces joining together the free ends of the bars; travelling Wheels mounted through the intermediary of bearings on the table bars; an electric motor and a transmission, kinematically connecting the motor to at least two travelling wheels which move on tracks made of sectional iron disposed laterally on each side of the work area.

According to another feature, the support chassis comprises a rectangular frame in sectional iron, whose frontal and rear bars are parallel to the longitudinal sides of the table frame and are capable of being moved long with these longitudinal sides; guiding abutments disposed on the chassis frame and bearing against the longitudinal sides of the table frame; and clamping means permitting the support chassis to be fixed in the position desired on the traverse table.

According to another feature, the ladle is mounted in the center of the support chassis and carries two crosspieces parallel to the direction of movement of the chassis, the ends of these cross-pieces resting, through the intermediary of shock absorbers, on the longitudinal sides of the chassis frame.

According to another feature, the ladle hopper is situated above the upper edge of the mold and comprises two vertical walls forming a part of the ladle walls and two inclined walls each having a distinctly different inclination, and at least one of which inclined walls is constituted by a movable flap, pivotally mounted on the two vertical walls of the hopper and is furnished with units for regulating the inclination of the flap, and the other of which walls is furnished with a vibrator.

According to another feature, the units for regulating the inclination of the movable flap comprise: a fixed support tube forming a cross-piece between the lower edges of the vertical hopper walls; a worm mounted on the flap through the intermediary of a nut and a guide piece, both of which are rigidly connected to the flap; a control wheel keyed to the upper end of the worm; and a shoe fixed to the other end of said worm by means of a safety-hook joint, this shoe being interposed between the lower end of the flap and the support tube.

According to another feature, the vibrator intended to induce vibrations in the tensed reinforcement is mounted in a pivoting manner on the chassis frame through the intermediary of a support-stirrup, suspended on tWo pivots from said frame, a plate furnished with a removable stand being interposed between the vibrator and a plurality of shock absorbers attached to the support-stirrup, the bottom of which presents an opening for the passage of the stand.

According to another feature, the bottom of the support stirrup is furnished with a mercury switch for the reinforcement vibrator.

These and other objects, features and advantages of the present invention will become more readily apparent from the following detailed description when taken together with the attached drawings, in which:

FIG. 1 is a perspective view of a concrete bar fabricated according to the process of the present invention;

FIG. 2 is a schematic plan view of an installation for fabricating the bars of FIG. 1;

FIG. 3 is a partial perspective view of a mold for fabricating the bars of FIG. 1;

FIG. 4 is a perspective view of one embodiment of a pair of adjacent end-pieces for two successive concrete bars;

FIG. 5 is a longitudinal cross-sectional view of one em bodiment of the traction apparatus;

FIG. 6 is a plan view of the apparatus for rendering certain steps of the process of the present invention auto= matic, or at least semi-automatic;

FIG. 7 is a side view of the apparatus of FIG. 6 looking in the direction of the arrow VII of FIG- 6;

FIG. 8 is a cross-sectional view taken along the plane VIIIVIII of FIG. 6;

FIG. 9 is a cross-sectional view taken along the plane IXIX of FIG. 6;

FIG. is a cross-sectional view taken along the plane X-X of FIG. 6; and

FIG. 11 is a cross-sectional view taken along the plane XIXI of FIG. 10.

The concrete bar shown in FIG. 1 is composed of a concrete body 1, a central reinforcement 2, and a seam reinforcement 3, intended for permitting the rigid connection of the bar to a compression table. The central reinforcement 2 extends beyond the ends of the bar and the extended portions 2a and 2b are bent back through 180 to form hooks for anchoring the bar.

FIG. 2 shows schematically an installation for fabricating these concrete bars in accordance with the present invention.

This installation comprises a plurality of molds M M M arranged side-by-side, a first carriage or holder, H for holding the reinforcements 2 (which are the same elements as the reinforcements 2 of FIG. 1), a second fixed carriage, or holder H which is arranged t place reinforcements 2 under tension, a third fixed carriage, or holder H whose function will be described below, an apparatus T for placing the reinforcements under tension, and an apparatus C for continuously monitoring this tension.

The molds M to M are preferably constructed in the manner shown in FIG. 3, of two channel irons 5 and 6, whose webs are arranged so as to be vertical and facing one another. Two cut-out pieces 7 and 8 are each welded to a respective channel iron and are held rigid with respect to each other by cross-pieces spaced along the length of the mold. One such cross-piece is shown in FIG. 3 as the element 9. With the aid of a set of cross-pieces 9, one can vary at will the spacing between the channel irons in accordance with the width desired for the bars to be molded. At least some of the cross-pieces 9 can comprise a hook member 9a transporting the molds.

The molds M to M are preferably constructed so as to have alength equal to several lengths of the bars to be molded; for this purpose several channel irons similar t the members 5 and 6 may be joined together end-to-end, either by welding or with the aid of fish joints, in order to achieve the desired length. The bottom of the molds is constituted by the flat surface upon which they rest.

The molds may also comprise flat irons 10 fixed on the upper flanges of respective channel irons 5 and 6 and extending beyond the webs of the channel irons towards the interior of the mold in order to form the longitudinal seatings 1a and 1b (see FIG. 1) on the bars; these seatings are intended to serve as supports for permanently placed pouring forms when the bars are eventually used in the fabrication of poured concrete flooring.

The transverse division of the molds is effected by endpieces, or forms. One set of such forms is shown in FIG. 4 to comprise: at least two similar pieces 11, each comprising a plate 11a whose shape corresponds to the cross-section of the mold; each plate having a slot 11b for permitting the placing of the end pieces over the tensed reinforcement 2; this slot being formed so that reinforcement 2 is centered when it rests at the bottom thereof.

Each plate 11a carries a rigidly mounted arm 11c perpendicular to the plate. The two arms 110 of the two pieces 11 are thus parallel to each other and are disposed on opposite sides of the reinforcement; an assembly element 12 permits the two arms to be rigidly connected together while pinching reinforcement 2.

Carriages H H and H are constituted by I-irons, having a normal profile, embedded vertically in concrete blocks; two horizontal I-irons having a similar profile, are fixed in these vertical bars in a spaced manner; a plurality of channel irons are disposed on the horizontal I-irons and are each pierced by a hole for the passage of a respective one of the reinforcement rods.

The anchoring carriage H is furnished with means, which may be of any well-known type, for gripping reinforcements 2 and these means are supported by the channel irons of the carriage.

The traction carriage H supports the traction apparatus T, which will be described below.

The retaining carriage H supports retaining means, such as jaws, for retaining the reinforcement rods 2, and the function and purpose of these retaining means will also be discussed below.

The apparatus T for placing the reinforcements 2 under tension or traction can be very simply constructed by means of a jack 28 employing a female screw 15 and nut 16, as may be seen in FIG. 2; the nut 16 is driven in rotation, through the intermediary of a chain 17, by the output shaft of a speed reducer 18 driven by a motor 19. All of these elements are carried by a stand 20.

The female screw 15 is traversed by the reinforcement 2 which is to be placed under tension and this reinforcement is rigidly held by a set of jaws 21 which is supported by the free end 15a of screw 15.

The apparatus C for continuously monitoring the tension to which reinforcement 2 is subjected may advantageously be constituted by a hydraulic dynamometer carrying an exterior barrel 25 supported by carriage H and an interior barrel 26 coaxial with barrel 25; a manometer 27 measures the pressure of the oil contained in an annular impermeable space provided between barrels 25 and 26 when a force is applied to the barrel 26.

The application of this force is effected by a tube 28 surrounding screw 15 and supported by the interior barrel 26. The tube 28 transmits to the monitoring apparatus C a compression which is proportional to the tension applied to reinforcement 2 by the apparatus T.

Such an installation functions in the following manner: The reinforcement rods 2, which are delivered on rolls, are arranged by causing them to traverse the anchoring means of carriage H and the retaining means of carriage H and H The monitoring apparatus C and the traction apparatus T are arranged in line with one of the reinforcement rods 2. Reinforcement rod 2 is then gripped by the anchoring means of carriage H and by the jaws 21.

The reinforcement rod 2 is then placed under tension in a. manner which will be explained in detail below; when the tension on reinforcement 2 has attained the desired tension, as determined by apparatus C, there are disposed along the reinforcement the various end-pieces constituted by the assemblies of the pieces 11 and the arms 11c are rigidly joined together in such a manner as to pinch reinforcement 2 by means of the assembly element 12.

A mold is then placed and centered with respect to the armature and the system is prepared for a pouring of concrete.

The placing of reinforcement 2 under tension is effectuated by operating the motor 19; the speed of rotation of nut 16 is adjusted so that the reinforcement rod 2 is stretched at the preferred rate of 2-3, mm./sec.

Since the reinforcement rod 2 is tobe subjected to a tensile stress which may attain to of its rupture limit and since this tension is applied to a reinforcement whose length is equal to the length of several concrete bars disposed in a lengthwise manner in the same mold M, the operation of placing reinforcement 2 under tension will produce a substantial elongation of the rod. It may occur therefore, that the end of rod 2 will travel a distance which is greater than the path of travel of screw 15 of apparatus T.

When this occurs, and screw 15 is at the end of its path of travel, the jaws of the retaining carriage H are closed on the rod, the jaws 21 are opened, and the screw 15 is returned to the starting point of its path of travel; the jaws 21 are then caused to re-grip the rod and the jaws of retaining carriage H are released; and the apparatus T is once again caused to go through a tensionapplying operation. The same series of steps may be carried out as many times as necessary to achieve the desired degree of tension on reinforcement rod 2.

Because this value of tension is very close to the rupture limit of the reinforcement, the tension applied must be constantly monitored by means of the apparatus C.

When the desired degree of tension is achieved, the jaws of the retaining carriage H, are caused to grip the rod and the apparatus T may then be transferred to a position where it can carry out the tension-applying operation on another reinforcement rod 2.

The pouring of concrete is effectuated with the seam reinforcement 3 disposed in the upper portion of the bar being formed; the poured concrete is compounded so as to have, after hardening, a compression resistance of the order of 250 kg./cm. and its granulometry is made so as to be compatible with the dimensions of the crosssections of the concrete bar, taking into account the crosssectional area of the central reinforcement.

The seam reinforcements 3 may be constituted by simple rods having round cross-sections and formed so as to have a generally sinusoidal longitudinal shape.

The pouring of the concrete is elfectuated while simultaneously causing it to vibrate; to this end, a vibrator is arranged in contact with the central reinforcement 2. This vibrator could be constituted by a small pneumatic or electric hammer, or any other type of known industrial vibrator and has not, because it is well-known, been shown in the drawings.

Since the central reinforcement is in the form of a taut metallic cord, it is induced, by well-known vibratory phenomena, to vibrate at a harmonic frequency which is substantially greater than the frequency of the vibrator. These vibrations have their maximum amplitude in the region of the axis of this reinforcement, i.e. in the regions where the concrete should, at least at the ends of the bar, possess the best adherence qualities and the best resistance to compression.

When the concrete has been poured, the tension is maintained on the reinforcement rod. However, the molds and the end-pieces are recovered for re-use after the concrete has hardened.

When the concrete has attained a sufficient hardness, the tension on reinforcement 2 is released so that the concrete is placed under compression; to this end the traction apparatus T is re-actuated in order to permit the freeing of the retaining jaws of carriage H and the motor 19 is then caused to turn in the reverse direction in order to completely free reinforcement rod 2.

The hardening of the concrete may be hastened by the provision of heating means for the bars.

The group of aligned bars are then separated by cutting the central reinforcement at points midway between the ends of adjacent bars, e.g. by means of a blow-torch and the portions of the reinforcement rods which extend beyond their respective concrete bar are bent in the form of an anchoring hook.

The bar thus fabricated is then ready for delivery from the fabrication plant.

To give one example of the quantity of production which could be achieved with the above-described apparatus, there could be disposed in a work-shop, having a length of 100 meters and a width of meters approximately 4 0 molds placed side-by-side, each mold permitting the fabrication of 12 bars aligned with one another and each having a length of 7 meters.

It should be obvious to one skilled in the art that the process and the apparatus forming the object of this invention permit the fabrication of pre-stressed concrete bars under conditions which permit particularly rapid fabrication at a correspondingly low price per bar.

As is shown in FIG. 5, the traction apparatus comprises a hollow stand 130 having one of its ends rigidly connected to a pressure tube 131; this tube is itself rigidly connected to a cylinder 132 in which slides a hollow piston 133 having two barrels furnished with sealing joints 133a and 1331).

The dynamometric chamber 134, defined by cylinder 132 and piston 133, is filled with an incompressible fluid; this chamber communicates with a pressure-sensitive switch, or manostat, 135 and with a graduated manometer 136.

A hollow screw 137 is mounted to slide in the stand 130 and the tube 131 between two extreme positions: in FIG. 5 this screw 137 has been shown in its extreme tensionapplying position in solid lines and, partially, in its extreme retracted position in broken lines.

The end of screw 137 which is furthest removed from chamber 134 carries a gripping-jaw arrangement 138 which is regulatable by means of a spring and screw arrangement, designated generally by numeral 139.

Screw 137 is externally threaded and is driven in a longitudinal direction by the rotation of nut 146. This nut is in turn driven by a rigidly connected wheel 140, having a toothed periphery and in turn driven through a chain by an electrical speed-reduction motor, which has not been shown in FIG. 5; this motor (see FIG. 2) is desirably of the two-speed type. The action of the nut 146 on screw 137 provokes a translational movement of the latter; screw 137 is effectively prevented from rotation by a heel 147 which is held between two abutment ramps mounted on stand 130, the heel 147 being rigidly joined to the jaw arrangement 138, which is in turn rigidly connected to the end of screw 137.

A series of roller bearings 141, 142a and 142b are provided to assure the positioning and the rotation of the various moving parts. A flexible sheet 143 is provided to protect the threads of screw 137 from dust.

Two switches 144 and 145 are mounted on the stand to indicate the arrival of screw 137 at either end of its path of travel.

The apparatus which has just been described, operates in the following manner: with the reinforcement 2 being laid out straight and having one of its ends fixed in the anchoring carriage H and its other end passing through the jaws of the retaining carriage H the traction apparatus is placed in such a manner that the exposed face of piston 133 bears against the traction carriage H (see FIG. 2).

The hollow screw 137 being in its extreme retracted position, as shown in broken lines, the free end of reinforcement 2 is introduced into the hollow piston 133, then, into the hollow screw 137 until the end of the reinforcement passes through the jaws 138.

The electric motor is put into operation, at its low speed, in a direction corresponding to the application of tension to the reinforcement 2, thereby provoking the rotation of toothed wheel and the displacement of hollow screw 137 from its extreme retracted position to its solid-line position. During this movement, the jaws 138 close over the reinforcement rod, whose extremity is displaced during the tensioning operation; this displacement takes place freely since the jaws of the retaining carriage H are so constructed as to permit the reinforcement rod to move in the direction of increasing tension.

When the hollow screw 137 has reached its extreme tension-applying position, as shown in solid lines in FIG. 5, the switch is operated to reverse the direction of rotation of the motor and to cause it to turn at its high speed. During this movement, the jaws 138 free the end of reinforcement rod 2 and this rod is automatically gripped by the jaws of the retaining carriage H When the hollow screw 137 has reached its extreme retracted position, that shown in broken lines, the switch 144 is operated to once again reverse the direction of rotation of the motor and to cause it to turn at its low speed in order to carry out a second tension-applying operation.

As has been noted previously, since the length of the reinforcement rod is equal to several times the length of a single concrete bar, the placing of the rod under tension will probably require several Successive cycles of operation of the traction unit T. The traction apparatus which has just been described permits this operation to be carried out any number of times in a completely automatic manner.

During the course of these operations the tension on reinforcement rod 2 may be monitored by the reading of a suitably graduated manometer 136. The pre-set, pressure-operated switch 135 operates to abruptly stop the driving motor when the tension on reinforcement rod 2 has reached the desired value.

By then causing the motor to turn in its reverse direction, the tension is maintained on the reinforcement rod by the jaws of retaining carriage H and the traction apparatus is liberated for movement to another position where it will place a second reinforcement rod under ten- The electrical system of the installation has not been shown in the drawings since such an arrangement is extremely well-known. This system may also comprise various types of visual or audible indicators when the tensionapplying operation for a reinforcement rod has been completed.

It may be appreciated from that which has been described above that the placing of a reinforcement rod under tension can be carried out rapidly and automatically and with a permanent control of the value of tension applied and a automatic stopping of the operation.

As is shown in FIGS. 6, 7 and 8, the apparatus for rendering certain operations automatic, or at least semiautomatic, comprises: a traverse table 201 which straddles the entire width of the work area and which can be displaced in the direction of the longitudinal axis of the bars to be fabricated, the extent of this displacement, which is equal to the length of said work area, is defined, at one end, by the anchoring carriage H and, at the other end, by the retaining carriage H and the traction carriage H at least one chassis 202, called a support chassis, disposed on the traverse table 201 and capable of being dis placed (e.g. by means of a travelling crane) on the latter perpendicularly to the direction of displacement of table 201; attachment means 203 for the metallic reinforcement rods placed on the traverse table 201; a concrete ladle 204, mounted on this support chassis 202 and furnished with at least one vibrator 205 for inducing vibrations in the walls 206 and 207 of the ladle hopper 208; at least two retractable vibrators 209 and 210 mounted in a pivotable manner on the support chassis 202 so as to each be on a respective side of the ladle 204 and so as to be along the axis of the tensed reinforcement rod, these vibrators being intended to induce vibrations in the reinforcement rod; control means 211 for the vibrators 209 and 210; regulating means 212 for regulating the slow opening of hopper 208; and driving means 213 for driving the traverse table 201.

The traverse table 201 is constituted by a rectangular frame made of channel irons, the longitudinal sides 214 and 215 of said frame being perpendicular to the direction of displacement of traverse table 201 and parallel to the carriages H H H and the channel irons 216 forming the transverse edges of said frame, being parallel to the direction of displacement of table 201; a series of channel irons 217 attached, e.g. by welding, at predetermined distances along the outer edge of sides 214 and 215 and perpendicular thereto; metal covering sheets (not shown in the drawings for purposes of clarity) disposed on the channel irons 217 in such a way as to form a travel path; cross-pieces 218 joining the free ends of channel irons 217; and rollers 219, whose axles are mounted by means of bearings or flanges 220 on corresponding channel irons 217 of the table 201, these rollers being displaceable on tracks 221, suitably disposed on either side of the Work area 222.

The forward edge of table 201 is situated along the longitudinal frame edge 214, i.e. on the side near the anchoring carriage, while the rear edge of table 201 is situated along the frame edge 215, i.e. near the retaining carriage H and the traction carriage H The rear edge of table 201 carries driving means 213 which are essentially constituted by an electric motor 223 furnished with a speed-reducer 223a and with a transmis sion comprising: a pinion 224 keyed to the output shaft of speed-reducer 223a, a second pinion 225'keyed to a power-transmission shaft 226 and connected to the first pinion 224 by means of a driving chain 227, a pair of third pinions 228, each fixed to one end of the powertransmission shaft 226, and a pair of control pinions 229, each rigidly connected to one of the rear rollers 219, corresponding ones of the pinions 228 and 229 being connected together by means of a driving chain 230.

As has been indicated above, the traverse table 201 is furnished with attachment means 203 for the reinforcement rods 2 which are to be placed in the work area 202 prior to being placed under tension between anchoring carriage H and traction carriage H To this end, the forward edge of traverse table 201 comprises attachment means 203 for the reinforcements.-

These means 203 are constituted by a series of pairs of arms 231 which are articulatable with respect to one another, the upper arm of each pair 231 being rigidly fixed to a corresponding channel arm 217 of the front edge of table 201 While all of the free ends of the lower bars are rigidly connected together by a horizontal crossmember 232 (which e.g. may be a channel iron), presenting either a plane surface or two edges situated in a horizontal plane when the arms 231 are unfolded, i.e. when they occupy a vertical position, and by a flat iron 233 capable of being held firmly against the cross-member 232 by means of a series of threaded bolts 233a, placed side-by-side passing through openings arranged in fiat iron 233 and fixed in cross-piece 232. The linkage between each pair of arms 231 is constituted by a hinge, or knuckle-joint, 231a and arranged in such a manner that the assembly of lower arms can be fixed in a vertical position (lower position of cross-members 232) in which position the upper ends of the lower arms abut against the lower ends of the upper arms, or the assembly of lower arms can be raised towards the rear of table 201 in an upper position in which the cross-piece 232 is removed from the plane of Work area 222. In this latter position the lower arms are attached to corresponding irons 217 by means, for example, of hooks.

In order to put the reinforcement rods into position, the work area must be entirely clear, i.e. the pouring molds M to M, must be removed beforehand from this area. All of the pairs of arms 231 are unfolded so that the cross-member 232 is in its lower position. The free ends of the reinforcement rods, which are stored behind the anchoring carriage H pass through the latter in such a way that they can be easily placed between the cross-piece 232 and the flat iron 233 which is then forcefully urged towards cross-piece 232 by means of the threaded bolts 233a, thus squeezing the free ends of reinforcement rods 2 against the cross-member 232. Because Of the particular way in which each pair of arms 231 are hinged together, the lower arms abut against the lower ends of the corresponding upper arms when the traverse table 201 is displaced towards the traction carriage H and the retaining carriage H in such a way that the lower arms remain in a vertical position. When the table 201 is displaced, it carries all of the reinforcement rods towards the traction carriage H and the table is stopped when the ends of the rods arrive at said carriage. The ends of reinforcement rods 2 are then freed, the cross-member 232 is raised, the traverse table 201 is returned towards the anchoring carriage H and the reinforcement rods are placed in position in the retaining carriage H and then in the traction carriage H Each support chassis 202 is constituted by a rec- 11 tangular frame whose front and rear edges are formed by angle irons 234 and 235 disposed parallel to the longitudinal channel irons 214 and 215 and capable of being displaced in a direction parallel to these longitudinal channel irons; by cross-members 238 and 239', parallel and perpendicular, respectively, to the angle irons 234 and 235 and forming, together with said angle irons and the ends of the longitudinal edges 236 and 237 of the support chassis 202, housings for the vibrators 209 and 210; by guiding abutments 240 and 24-1, attached to the frame of chassis 202, and limiting the relative displacement of the chassis 202 with respect to the table 201 in the direction of movement of the latter by the possible bearing of the abutments 240 and 241 against one of the longitudinal edges 214 and 215 of table 201; and by blocking means, such as removable abutments (not shown) serving to prevent any relative movement of the chassis 202 with respect to table 201 in a direction perpendicular to the direction of movement of said table 201.

Each of the longitudinal edges of chassis 202 carries two support plates 242, 243 and 244, 245, respectively, arranged in such a manner that the four support plates 242, 243, 244 and 245 of chassis 202 constitute the corners of a rectangle centered on the chassis.

The concrete ladle 204 comprises four vertical walls and has a rectangular cross-section. To each of the pair of narrow walls of the ladle are welded, riveted, or bolted a respective one of the metallic girders 246 and 247 (which may be made of channel irons) Whose ends are rigidly connected to supporting cross-members 248 and 249 which in turn have their ends resting, through the intermediary of suitably dimensioned damping devices 2-50, 251, 252, and 253, on the support plates 242, 243, 244 and 245, respectively. It should also be noted that the ends of girders 246 and 247 do not rest directly on the ends of cross-members 248 and 249, but are slightly displaced towards the centers of the cross-members.

As may be most clearly seen in FIGS. 8 and 9, each of the concrete ladies 204 comprises at its lower end a hopper 208 presenting, on the one hand, two vertical lateral walls 254 and 255 which are nearly prolongations of the corresponding walls of the ladle and, on the other hand, two inclined walls 206 and 207, each of which has a different slope. At least one of the inclined walls 206 and 207 is made movable. In the present case, it is the wall 207 which is made movable, this wall being constituted by a pivotable shutter, or flap, 256 pivotally mounted near its upper edge on the lateral vertical walls 254 and 255 of the hopper 208, these vertical walls extending downward beyond the plane of the shutter in order to prevent leakage between shutter 207 and vertical walls 254 and 255. The other inclined Wall 206 of hopper 208 could also be made movable or could be fixed and is generally furnished with a vibrator 205. According to the embodiment shown in FIG. 9, the shutter 207 has a shallower slope than the wall 206. It would also be possible to render the more inclined wall 206 movable and to mount the other wall 207 in a fixed manner on the vertical walls 254 and 255. In either case, the vibrator 205 will always be attached to the fixed inclined wall of the hopper 208.

The organs 212 for regulating the inclination of shutter 207, i.e. for controlling the concrete-pouring opening 257, are constituted by: a support tube 258, forming a crosspiece between the lower ends of the vertical walls 254 and 255 of hopper 208; by a worm 259, mounted on the movable shutter 207 through the intermediary of a nut 260 and a guide piece 261, both of which are rigidly connected to shutter 207; by a control wheel 262, keyed to the upper end of worm 259; and by a wedge 263, attached to the other end of the worm 259 by means of a spring-clipped joint, this wedge 263 being interposed between the lower end of shutter 207 and the support tube 258. It may be readily understood that, when the wedge 263 is advanced, the shutter 207 is urged against the lower end of the inclined Wall 206 in such a way that the concrete-pouring opening 257 assumes the shape of a slot having a controllable width.

As may be seen in FIGS. 8, l0, and 11, each of the vibrators 209 and 210, disposed on respective sides of the concrete ladle 204 and along the axis of the concretepouring opening 257, is mounted in a pivoting manner on the frame of chassis 202. To this end, the two abutments 240 and 241, serving, as has been described previously, as guiding abutments and suitably attached, on the one hand, to the longitudinal edge 236, and on the other hand, to the cross-piece 239 of chassis 202, are connected by means of respective pivots 264 and 265 to a support stirrup 266 whose base plate 267 supports the base plate 268 of one of the vibrators 209 and 210. Vibration absorbers 269 are interposed between the base 267 and the base plate 268. To base plate 268 is attached a vibration prop 271 passing through an opening 270 in the base 267 of stirrup 266. The lower part of prop 271 is constituted by an organ 271a Which is interchangeable and whose height is regulatable. This permits the use of organs 271 having different shapes and adapted to whatever form the reinforcements to be placed in vibration may have. These reinforcements for example could be in the form of several metallic wires with or without an auxiliary reinforcement rod. In order to make the center of gravity of the vibrator-prop assembly as low as possible, the organ 271a is given as large a mass as possible. This permits the vibrator-prop assembly to automatically assume, under the effect of its own weight, its vertical equilibrium position during the times when the reactions to the impulsions given to the reinforcement tend to urge the prop 271 into an inclined position. The two abutments 240 and 241 are connected together and made rigid by means of two stiffening tubes 272 and 273 and two threaded shanks 274 and 275, attached at their ends to the abutments 240 and 241 by means of nuts 276 and 277.

The base 276 of stirrup 266 is furnished with a mercury switch 211 which permits the automatic starting and stopping of the vibrators 209 and 210. This switch is hinged to the base 267 and may occupy various inclined positions with respect to said base, the pivoting axis of the switch 211 being perpendicular to the plane in which prop 271 pivots. In this manner, it is possible to determine the desired limit of inclination of the prop 271 with respect to the vertical, and to adjust the orientation of switch 211 so that when this limit is reached, the vibrator will be turned off.

The vibrator-prop assembly can be raised towards the interior of the chassis and there attached in a removable manner.

There has been described above a process for the fabrication of a plurality of aligned concrete bars by means of a single mold, the adjacent ends of successive bars being limited by the end pieces 11 (FIG. 4) which occupy, on the reinforcement rod 2, a length which is not to be surrounded by concrete. In the present case, there are provided on the end pieces 11 pans or drain-channels for isolating these portions of the reinforcements from the concrete.

For the fabrication of various types of prestressed concrete construction elements, such as bars, beams, panels, etc., the reinforcement rods are first suitably extended between the anchoring carriage H and the traction carriage H and retaining carriage H as has already been discussed, and the reinforcement rods are moved with the aid of the table 201. Once the reinforcement rods have been placed under tension, the molds M to M are installed, then the chassis 202 is moved (e.g. by means of a travelling crane) on the work table 201 in such a way as to lead the concrete-pouring opening 257 of the pocket 204 and the prop 271a over the tensed reinforcement rod 2. Then the chassis 202 is suitably locked in place on the table 201. The vibrator which is ahead of the ladle 204 in the direction of displacement of said chassis (in the embodiment shown in the present drawing, it is vibrator 210 which is in front of the ladle), is placed in its work position in which it induces vibrations in reinforcement rods 2 and, through the intermediary of these rods, in the concrete which has been poured through opening 257 (FIGS. 6 and 8). When the organs 271a of the prop 271 encounters an obstacle, such as an end-piece 11, the vibrator-prop assembly inclines and, as a result, the mercury switch 211 is operated to turn ofi the vibrator. The vibrator is once again turned on automatically when the vibrator-prop assembly reassumes its normal vertical position.

It should be appreciated that the process and apparatus which have just been described are capable of undergoing many modifications and variations without departing from the spirit of the present invention. Thus, for example, the concrete-pouring opening 257 could be arranged so that its longitudinal axis is perpendicular to the direction of displacement of table 201, the chassis 202 could be furnished with rollers, etc. It should therefore be understood that the coverage of the present invention should be limited only by the scope of the annexed claims.

I claim:

1. Apparatus for simultaneously fabricating a plurality of concrete bars containing at least one resilient longitudinal reinforcing rod, comprising:

(a) at least one pouring mold constituted by a plurality of longitudinally aligned end abutting pairs of channel irons, all of which have their webs oriented vertically, with the webs of each pair of irons facing one another, means rigidly connecting each of said irons to the irons abutting it, and adjustable crosspieces connecting at least several of said pairs of irons together so as to permit the distance between said webs to be varied, the length of said mold being equal to several times the length of each bar to be molded;

(b) a plurality of pairs of end-pieces disposed in said at least one mold, each of said pairs of end-pieces defining the adjacent ends of two adjacent concrete receiving regions, each of said end-pieces having an opening therein for the passage of said reinforcing rod, the longitudinal distance between the end-pieces of each pair being equal to twice the distance by which said rod is to extend beyond each end of each bar;

() longitudinally extending attachment means connected to each pair of end-pieces and having gripping means for gripping said rod between said attachment means;

((1) means disposed at each end of said mold for placing said rod under tension;

(e) movable table means mounted above said mold for rendering at least some of the bar fabrication operations at least semi-automatic; and

(f) means mounted on said movable table for inducing vibrations in the concrete while the latter is being poured into said mold.

2. An apparatus as recited in claim 1 wherein each of said end-pieces comprises an end plate defining one end of one of said bars and placed transversely in said mold, said attachment means comprises an arm rigidly connected to said plate and extending perpendicular thereto into the region separating the pair of end-pieces of which it forms a part, said opening being defined by a slit which extends from one edge to the center of said plate, the arms of each pair of end pieces extending to either side of, and parallel to, the axis along which said rod is to be placed, and wherein the gripping means for each pair of end pieces is connected to the arms of said pair.

3. Apparatus according to claim 1 wherein the means for placing said reinforcement rod under tension comprise, in combination: a fixed anchoring carriage for one end of said reinforcement rod, comprising clamping means for said rod; a fixed traction carriage for tensing said rod and a fixed carriage for restraining said rod; a traction apparatus supported by the traction carriage and comprising a jack acting on said rod to be tensed; and an apparatus for continuously monitoring the tension on said rod.

4. Apparatus according to claim 3 wherein the jack of said traction apparatus comprises a screw-jack operated by an electric motor operating through a speed-reducer, said jack having a hollow screw for receiving one end of said rod, and a retaining jaw for gripping said rod, said jaw being supported by one end of said screw, said screw being mounted to move longitudinally in said jack.

5. Apparatus as recited in claim 4 wherein said jack further comprises a hollow tube having one end connected to said jack, said tube being coaxially aligned, with, surrounding, and longitudinally movable with respect to, said hollow screw; and wherein said tension monitoring means comprises a hydraulic dynamometer comprising two barrels coaxially mounted to slide longitudinally with respect to one another and having a longitudinal bore for the passage of said rod; an incompressible fluid disposed between said barrels; and a manometer mounted on one of said barrels for measuring the pressure of said fluid with one of said barrels being mounted on said traction carriage and the other of said barrels supporting the other end of said tube.

6. Apparatus as recited in claim 3 wherein said screw is externally threaded and wherein said jack further comprises: a rotatable nut engaging the threads of said screw; an externally toothed wheel coaxial with said screw and rigidly connected to said nut; a reduction motor driving said wheel; means for preventing rotation of said screw; a pair of switches mounted to each to be actuated when said screw arrives at a respective end of its longitudinal travel path; and a switch responsive to the indication of said manometer for stopping said motor when a predetermined pressure has been reached.

7. Apparatus as recited in claim 3 wherein said movable table means for rendering at least some of the operations at least semi-automatic comprises:

(a) a traverse table straddling the entire width of the area occupied by said at least one pouring mold and movable along the longitudinal axis of said mold between the ends of said area occupied by said at least one mold;

(b) one of said ends of said area being delimited by said anchoring carriage and the other of said ends thereof being delimited by said restraining carriage and said traction carriage;

(c) at least one support chassis disposed on said traverse table and displaceable in a direction perpendicular to the direction of displacement of said table;

(d) means for fixing said reinforcement rod to said table;

(e) at least one concrete pouring ladle having a hopper at its lower end, said ladle being mounted on said chassis and said hopper having a regulatable pouring opening;

(f) auxiliary vibrator means mounted on said hopper near said opening for vibrating the hopper walls in order to improve the flow of concrete;

(g) means for regulating said pouring opening of said hopper; and

(h) means for driving said traverse table and said support chassis; and wherein said means of claim It comprises: at least two retractable vibrators mounted in a pivotable manner on said support chassis and to either side of said ladle along the longitudinal axis of said at least one mold, and vibrator control means.

8. Apparatus as recited in claim 7 wherein said means for fixing said reinforcement rod to said table comprises:

(a) a series of pairs of arms, the upper arm of each 15 pair being vertically oriented and having its upper end rigidly connected to the edge of said table adjacent said anchoring carriage, and the lower arm of each pair having one end connected to the lower end of its respective upper arm in such a way as to permit the arms of each pair to pivot with respect to one another about a horizontal axis parallel to said leading end of said table between a position where the arms of each pair are vertically aligned and abutting and a position where said lower arm of each pair is raised and directed towards the edge of said table removed from said anchoring carriage;

(b) a cross-bar rigidly connecting together the free ends of said lower arms of all of said pairs of arms, said cross bar being connected to that surface of each lower arm which faces said anchoring carriage when said lower arms are in their vertical position;

() a flat bar placed upon said cross-bar so as to be horizontal when said lower arms are vertical; and

(d) a plurality of threaded bolts holding said flat bar to said cross bar.

9. Apparatus as recited in claim 7 further comprising a pair of iron tracks each of which is disposed along a respective side of the area straddled 'by said table, and wherein said table comprises:

(a) a rectangular frame made of channel irons, the longitudinal side of which frame are perpendicular to the direction of movement of said table;

(b) a plurality of channel bars attached between, and perpendicular to, said longitudinal sides of said frame;

(0) covering sheets placed on said channel bars so as to form a travel path for said chassis;

(d) cross-pieces joining together corresponding ends of adjacent pairs of said channel bars; and

(e) traveling wheels supporting said table and mounted to roll along said tracks.

10. Apparatus according to claim 9 wherein said support chassis comprises: a rectangular frame in sectional iron whose frontal and rear bars are parallel to the longitudinal sides of said table frame, means for moving said chassis frame along the axis of said longitudinal sides; guiding abutments disposed on the chassis frame and bearing against said longitudinal sides of the table frame; and clamping means permitting the support chassis to be fixed in the position desired on said traverse table.

11. Apparatus according to claim 10 wherein said ladle is mounted in the center of said support chassis and comprises two cross-pieces parallel to the direction of movement of the chassis, and shock absorbers upon which the ends of these cross-pieces rest said shock absorbers being mounted on the longitudinal sides of said chassis frame.

12. Apparatus according to claim 11 wherein said ladle-hopper is situated above the upper edge of the mold and comprises two vertical walls forming a part of the ladle walls and two inclined walls each having a distinctly different inclination, and at least one of which inclined walls is constituted by a movable flap pivotally mounted on the two vertical walls of the hopper and furnished with units for regulating the inclination of the flap, and the other of which walls is furnished with said auxiliary vibrator.

13. Apparatus according to claim 12 wherein said units for regulating the inclination of the movable flap comprise: a fixed support tube forming a cross-piece between the lower edges of the vertical hopper walls; a worm mounted on the flap through the intermediary of a nut and a guide-piece, both of which are rigidly connected to the flap; a control wheel keyed to the upper end of the worm; and a wedge fixed to the other end of said worm by means of a safety-hook joint, this wedge being interposed between the lower end of the flap and the support tube.

14. Apparatus as recited in claim 7 wherein said vibration including means comprises at least one vibrator mounted to induce vibrations directly in said rod.

15. Apparatus as recited in claim 14 wherein said vibrator for inducing vibrations in said rod comprises: a vibration inducing mechanism; a support stirrup pivotally mounted on said chassis; a plurality of shock absorbers mounted on said stirrup; and a plate mounted on said shock absorber, supporting said mechanism, and furnished with a normally downwardly-directed prop; the bottom of said stirrup having an opening for the passage of said prop.

16. Apparatus as recited in claim 15 wherein said vibrator further comprises a mercury switch mounted on said stirrup and electrically conected so that its angular orientation controls the turning on and the turning off of said mechanism.

References Cited UNITED STATES PATENTS 2,966,717 1/1961 Fuller et al. 25-118 X 3,207,829 9/1965 Nieber et al. 264228 3,217,375 11/1965 Kinnard 25118 X FOREIGN PATENTS 561,135 5/ 1944 Great Britain.

J. SPENCER OVERHOLSER, Primary Examiner ROBERT D. BALDWIN, Assistant Examiner US. Cl. X.R.' 25-118 

